w_getmntent -- Get Mounted File System Information

SYNOPSIS

 #include <sys/mntent.h>

 int w_getmntent(void *sysInfo, int infoSize);

DESCRIPTION

w_getmntent gets information about the mounted file systems and saves that information in w_mntent structures, declared in <sys/mntent.h>. The arguments to w_getmntent are:

sysInfo: is a pointer to a buffer area used to save the file system information. The w_getmntent function copies a w_mntent structure into this area for each file system that is mounted.
infoSize: specifies the size of the sysInfo buffer area. If you are not sure of the required size, you can specify a 0, which will cause the w_getmntent function to return the number of file systems without actually copying any w_mntent information.

The w_mntent structures contains entries that provide the following information:

mnt_fsname: is the name of a mounted file system. This name can be up to 45 characters in length and ends with a NULL character. You can use this name with the w_statfs function to obtain more information.
mnt_dir: is the null-terminated directory name for the mounted file system.

A w_mnth structure, which is also declared in <sys/mntent.h>, is stored at the beginning to the sysInfo buffer area, before any of the w_mntent structues. The w_mnth structure forms a buffer area header that contains positioning information that is used when multiple calls to w_getmntent are made to store information about several mounted file systems. The following w_mnth entries are used:

mnth_size: is the size in bytes of the buffer area.
mnth_cur: is the current position in the buffer area.

The positioning information should be initialized to 0s and should not be changed between calls to the w_getmntent function. Subsequent calls to w_getmntent will append new w_mntent structures to the buffer area. A 0 is returned by w_getmntent after information about the last file system has been written to the buffer area.

RETURN VALUE

If successful, w_getmntent returns the number of w_mntent structures that have been copied to the buffer area. If infoSize was 0, the total number of file systems is returned, but no data are copied. A -1 is returned if w_getmntent is unsuccessful.

PORTABILITY

The w_getmntent function may be useful in OpenEdition applications; however, it is not defined by the POSIX.1 standard and should not be used in portable applications.

EXAMPLE

The following example illustrates the use of w_getmntent to obtain information about a mounted file system:

  #include <sys/types.h>
  #include <sys/mntent.h>
  #include <string.h>
  #include <stdio.h>

  #define MAX_FILE_SYS 10

  main()
  {
     int lastSys = 0, sysCount;

     struct {
        struct w_mnth header;
        struct w_mntent fileSysInfo[MAX_FILE_SYS];
     } bufferArea;

     memset(&bufferArea, 0, sizeof(bufferArea));

     do {
        lastSys = w_getmntent((char *)
                  &bufferArea, sizeof(bufferArea));
        if (lastSys == -1)
           perror("Error during call to w_getmntent.");
        else {
           for (sysCount = 0; sysCount < lastSys; ++ sysCount) {
              printf("File System = %sn",
                    bufferArea.fileSysInfo[sysCount].mnt_fsname);
              printf("Mount Point = %snn",
                    bufferArea.fileSysInfo[sysCount].mnt_mountpoint);
            }
        }
     } while (lastSys < 0);
  }

RELATED FUNCTIONS

mount, w_statfs